Rotating shafts are commonly utilized to transmit mechanical energy between power sources and power outputs. In many instances, a power source and output cannot be accurately aligned, or, these components move relative to one another during operation. In this regard, separate shafts may be connected to each component while the shafts are interconnected with a universal joint capable of transmitting rotation therebetween while the shafts are not coaxially aligned.
A common universal joint utilized to interconnect shafts for rotation is a cruciform-type universal joint. This cruciform-type joint includes a pair of U-shaped members (i.e., yokes) with their midpoints attached to the end of first and second shafts. The open ends of the two U-shaped yokes are positioned in a facing relationship and rotated 90° relative to one another. A cruciform connecting member including four radially extending torque bearing elements extends between the legs of each U-shaped yoke. Each radially extending torque-bearing element typically includes a coaxially aligned cap, which is lined with bearings. Accordingly, when two opposing torque bearing elements are interconnected to the legs of a U-shaped yoke, a pivotal connection is formed between the cruciform member and the U-shaped yoke.
The internal connection of two facing U-shaped yokes by the cruciform connecting member limits the range of movement between the rotational axes of two interconnected shafts. Further, as the angle between the rotational axes of the two shafts increases there is a loss of rotational efficiency between the shafts resulting in undesirable vibration. This vibration may lead to increased joint wear and shortened component life. Additionally, when subject to high loads, the cruciform connecting member is susceptible to cracking between adjacent ones of the torque bearing elements due to high stress concentrations.